Java HashMap replaceAll() Method
Java HashMapThe replaceAll() method replaces all mappings in the hashMap with the result of executing the given function.
The syntax of the replaceAll() method is:
hashmap.replaceAll(Bifunction<K, V> function)
Note:hashmap is an object of the HashMap class.
Parameter Details:
- function - the function to execute
Return Value
It does not return any value; it only replaces all values in the HashMap.
Example
The following example demonstrates the use of the replaceAll() method:
Example
import java.util.HashMap;
class Main {
public static void main(String[] args) {
// Create a HashMap
HashMap<Integer, String> sites = new HashMap<>();
// Add some elements to the HashMap
sites.put(1, "Google");
sites.put(2, "Example");
sites.put(3, "Taobao");
System.out.println("sites HashMap: " + sites);
// Change all values to uppercase
sites.replaceAll((key, value) -> value.toUpperCase());
System.out.println("Updated HashMap: " + sites);
}
}
class Main {
public static void main(String[] args) {
// Create a HashMap
HashMap<Integer, String> sites = new HashMap<>();
// Add some elements to the HashMap
sites.put(1, "Google");
sites.put(2, "Example");
sites.put(3, "Taobao");
System.out.println("sites HashMap: " + sites);
// Change all values to uppercase
sites.replaceAll((key, value) -> value.toUpperCase());
System.out.println("Updated HashMap: " + sites);
}
}
Executing the above program produces the following output:
sites HashMap: {1=Google, 2=Example, 3=Taobao}
Updated HashMap: {1=GOOGLE, 2=EXAMPLE, 3=TAOBAO}
(key, value) -> value.toUpperCase()It is an anonymous function lambda expression. It converts all values in the HashMap to uppercase and returns them. To learn more, visitJava Lambda Expressions。
Replace all values with the square of the key:
Example
import java.util.HashMap;
class Main {
public static void main(String[] args) {
// Create a HashMap
HashMap<Integer, Integer> numbers = new HashMap<>();
// Add mappings to the HashMap
numbers.put(5, 0);
numbers.put(8, 1);
numbers.put(9, 2);
System.out.println("HashMap: " + numbers);
// Replace all values with the square of the key
numbers.replaceAll((key, value) -> key * key);;
System.out.println("Updated HashMap: " + numbers);
}
}
class Main {
public static void main(String[] args) {
// Create a HashMap
HashMap<Integer, Integer> numbers = new HashMap<>();
// Add mappings to the HashMap
numbers.put(5, 0);
numbers.put(8, 1);
numbers.put(9, 2);
System.out.println("HashMap: " + numbers);
// Replace all values with the square of the key
numbers.replaceAll((key, value) -> key * key);;
System.out.println("Updated HashMap: " + numbers);
}
}
Executing the above program produces the following output:
HashMap: {5=0, 8=1, 9=2}
Updated HashMap: {5=25, 8=64, 9=81}
Other Extensions